The redevelopment of the Priory Hall apartment complex in north Dublin will cost about €27 million, almost €17 million more than had been estimated.

Work has started in recent weeks on the reconstruction of the fire-trap complex built in 2007 by former IRA hunger striker Tom McFeely. It was evacuated on the orders of the High Court nearly three years ago.

The council last year agreed to undertake the refurbishment at a cost estimated at just over €10 million. Banks agreed to write off debts of owner-occupiers and buy-to-let owners were given a moratorium on mortgage payments.

The redevelopment now under way is a more extensive reconstruction project than originally planned and also involves the removal of pyrite, according to the council’s executive manager for housing management Gerry Geraghty.

“The original plan was to bring the apartments back up to specification and for the people living there to go back in – but people didn’t want to go back,” he said.

The decision was taken to reconstruct the entire complex, including unfinished apartments, to “market standard” and offer them for sale, he said.

“There will be about €20.6 million in pure building costs. When you add in the extras it will come to about €27 million.”

Properties owned by Mr McFeely will be sold to cover part of this cost.

At the time of the evacuation in October 2011, 62 apartments were owner-occupied, 23 were buy-to-let, 35 were social housing , and 65 – in various states of completion – were owned by Mr McFeely, subsequently taken over by the Irish Bank Resolution Corporation.